Millions watched Donald Trump's inauguration from home, per Nielsen ratings

Videos and images on social media are comparing Donald Trump's inauguration crowd to Barack Obama's. But that's just half the story.

According to the Nielsen Co., which tracks TV-watching habits, a lot of people watched the inauguration from home — nearly 31 million.

SEE MORE: What Trump Fans (And Critics) Are Expecting From His Presidency

Nielsen didn't factor in online streaming, so viewership of the inauguration might have been even higher.

That number surpasses the inaugurations for George W. Bush, George H.W. Bush and Bill Clinton, but not Obama's first inauguration.

RELATED: Inaugural balls to honor President Donald Trump

Nearly 38 million people watched Obama take the oath of office in 2009.

President Ronald Regan holds the record with almost 42 million people tuning in to his ceremony in 1981.

Nielsen has been tracking inauguration viewers since 1969, and overall, Trump's total ranks fifth.